Add registrant api companies endpoint

app/controllers/api/v1/registrant/companies_controller.rb

@@ -0,0 +1,41 @@
+require 'serializers/registrant_api/company'
+
+module Api
+  module V1
+    module Registrant
+      class CompaniesController < ::Api::V1::Registrant::BaseController
+        def index
+          limit = params[:limit] || 200
+          offset = params[:offset] || 0
+
+          if limit.to_i > 200 || limit.to_i < 1
+            render(json: { errors: [{ limit: ['parameter is out of range'] }] },
+                   status: :bad_request) && return
+          end
+
+          if offset.to_i.negative?
+            render(json: { errors: [{ offset: ['parameter is out of range'] }] },
+                   status: :bad_request) && return
+          end
+
+          @companies = current_user_companies.drop(offset.to_i).first(limit.to_i)
+
+          serialized_companies = @companies.map do |item|
+            country_code = current_registrant_user.country.alpha3
+            serializer = ::Serializers::RegistrantApi::Company.new(company: item,
+                                                                   country_code: country_code)
+            serializer.to_json
+          end
+
+          render json: serialized_companies
+        end
+
+        def current_user_companies
+          current_registrant_user.companies
+        rescue CompanyRegister::NotAvailableError
+          nil
+        end
+      end
+    end
+  end
+end